Theoretical study of industrial scale closed-loop recycling counter-current chromatography separations

2020 ◽  
Vol 1633 ◽  
pp. 461630 ◽  
Author(s):  
Artak E. Kostanyan ◽  
Vera V. Belova
Keyword(s):  
Closed Loop ◽  
Theoretical Study ◽  
Industrial Scale ◽  
Counter Current

scholarly journals Asymptotic Behavior of a Viscoelastic Fluid in a Closed Loop Thermosyphon: Physical Derivation, Asymptotic Analysis, and Numerical Experiments

2013 ◽  
Vol 2013 ◽  
pp. 1-20 ◽  
Author(s):  
Justine Yasappan ◽  
Ángela Jiménez-Casas ◽  
Mario Castro
Keyword(s):  
Asymptotic Behavior ◽  
Viscoelastic Fluid ◽  
Closed Loop ◽  
Theoretical Study ◽  
Equations Of Motion ◽  
Asymptotic Properties ◽  
Inertial Manifold ◽  
Thermal Gradients ◽  
External Temperature ◽  
First Time

Fluids subject to thermal gradients produce complex behaviors that arise from the competition with gravitational effects. Although such sort of systems have been widely studied in the literature for simple (Newtonian) fluids, the behavior of viscoelastic fluids has not been explored thus far. We present a theoretical study of the dynamics of a Maxwell viscoelastic fluid in a closed-loop thermosyphon. This sort of fluid presents elastic-like behavior and memory effects. We study the asymptotic properties of the fluid inside the thermosyphon and the exact equations of motion in the inertial manifold that characterizes the asymptotic behavior. We derive, for the first time, the mathematical derivations of the motion of a viscoelastic fluid in the interior of a closed-loop thermosyphon under the effects of natural convection and a given external temperature gradient.

Isolation and Purification of Five Phloroglucinol Derivatives From Agrimonia Pilosa Ledeb by Counter-Current Chromatography Using Non-Aqueous Solvent Systems

2020 ◽  
Author(s):  
Lulu Fu ◽  
Chenghua Lu ◽  
Shengqiang Tong ◽  
Min Xu ◽  
Lan Tang ◽  
...  
Keyword(s):  
Closed Loop ◽  
Solvent System ◽  
The Other ◽  
Second Step ◽  
Two Phase ◽  
Isolation And Purification ◽  
Aqueous Solvent ◽  
Phloroglucinol Derivatives ◽  
Solvent Systems ◽  
Counter Current

Abstract Five non-polar phloroglucinol derivatives, viz. pseudo-aspidin, α-kosin and agripinol A-C were isolated and purified from Agrimonia pilosa Ledeb by semi-preparative counter-current chromatography. The separation was performed by a two-step elution with non-aqueous solvent systems. In the first step, an elution mode of a two-phase solvent system consisting of n-hexane-acetonitrile-dichloromethane-methanol (6:6:0.5:0.5, v/v/v/v) was used. We obtained sample Ι containing three components (47.0 mg) and sample ΙΙ containing two components (24.8 mg) from crude extract (371.0 mg). In the second step, sample Ι was successfully separated by closed-loop recycling mode with a solvent system consisting of n-hexane-acetonitrile-dichloromethane (10:7:3, v/v/v), yielding 17.8 mg of pseudo-aspidin, 18.5 mg of α-kosin and 6.4 mg of agripinol A. The other two compounds—8.7 mg of agripinol B and 13.6 mg of agripinol C—were obtained from sample ΙΙ in the same manner. All the isolated compounds had a high purity exceeding 95%.

Analysis and design of a PWM chopper-on/off control via a second order filter

2014 ◽  
Vol 11 (2) ◽  
pp. 181-186 ◽  
Author(s):  
Abdelouahab Zaatri ◽  
Souad Belhour
Keyword(s):  
Pulse Width ◽  
Closed Loop ◽  
Pulse Width Modulation ◽  
Theoretical Study ◽  
Second Order ◽  
Power Supplies ◽  
Analysis And Design ◽  
System Parameters ◽  
Order Filter ◽  
The Relationship

This paper presents the analysis of a nonlinear on/off control system including a filter of a second order in the closed loop. The proposed system is capable of generating a pulse width modulation which is used to design and built up a PWM (Pulse Width Modulation) chopper dedicated to regulate fluctuating power supplies such as photovoltaic, wind turbine systems; etc. The use of the second order filter aims to compensate the output against the fluctuations of irradiation as well as the variation of the load. The study essentially focuses on determining the relationship between the pulse durations with respect to system parameters and technological requirements. The theoretical study is followed by a simulation of a DC-DC chopper.

scholarly journals Analytical, Preparative, and Industrial-Scale Separation of Substances by Methods of Countercurrent Liquid-Liquid Chromatography

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 6020
Author(s):  
Artak A. Kostanyan ◽  
Andrey A. Voshkin ◽  
Vera V. Belova
Keyword(s):  
Steady State ◽  
Closed Loop ◽  
Load Capacity ◽  
Scale Up ◽  
Industrial Scale ◽  
Separation Processes ◽  
Immiscible Liquids ◽  
Pure Compounds ◽  
High Load Capacity ◽  
Liquid Chromatographic

Countercurrent liquid-liquid chromatographic techniques (CCC), similar to solvent extraction, are based on the different distribution of compounds between two immiscible liquids and have been most widely used in natural product separations. Due to its high load capacity, low solvent consumption, the diversity of separation methods, and easy scale-up, CCC provides an attractive tool to obtain pure compounds in the analytical, preparative, and industrial-scale separations. This review focuses on the steady-state and non-steady-state CCC separations ranging from conventional CCC to more novel methods such as different modifications of dual mode, closed-loop recycling, and closed-loop recycling dual modes. The design and modeling of various embodiments of CCC separation processes have been described.

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